examples/appsink-src: fix caps and appsrc properties to make the example work
examples/appsink-src: fix caps and appsrc properties to make the example work

detrout/qt-gstreamer,tswindell/qt-gstreamer,knuesel/qt-gstreamer,dejunk/gstreamer,GStreamer/qt-gstreamer,nasserGanjali/QtGStreamer,iperry/qt-gstreamer,detrout/qt-gstreamer,tswindell/qt-gstreamer,freedesktop-unofficial-mirror/gstreamer__qt-gstreamer,nasserGanjali/QtGStreamer,GStreamer/qt-gstreamer,detrout/qt-gstreamer,knuesel/qt-gstreamer,freedesktop-unofficial-mirror/gstreamer__qt-gstreamer,nasserGanjali/QtGStreamer,iperry/qt-gstreamer,dejunk/gstreamer,dejunk/gstreamer,GStreamer/qt-gstreamer,tswindell/qt-gstreamer,knuesel/qt-gstreamer,iperry/qt-gstreamer,freedesktop-unofficial-mirror/gstreamer__qt-gstreamer